Can Air Pollution Trigger a Heart Attack?

Air pollution may be behind more heart attacks than we think.

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There are 1.5 million heart attacks in the United States each year, accounting for more than 500,000 deaths annually. About half of these deaths occur within one hour of the heart attack, often outside of a hospital. Because heart attacks are often fatal, prevention is key. There are many ways that adults can reduce their chances of having a heart attack, like by controlling blood pressure and cholesterol or quitting smoking. But there are some cardiovascular risk factors that we can’t control, such as family history and age. Experts have long suspected that a lesser-known risk factor—air pollution—could be the cause of some heart attacks, particularly in industrialized countries.

Although some forms of air pollutants are naturally occurring, the most harmful pollutants are results of the modern world, from motor vehicles to power plants and landfills. Since the 1900s, many studies have shown that air pollution can have many negative effects on our health, particularly around hospital admissions and respiratory and cardiovascular mortality. But findings have not been consistent about whether pollution can actually trigger heart attacks.

To investigate, researchers analyzed results from 34 studies containing data on heart attack and short-term exposure to all of the major air pollutants: ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, and particulate matter. The results of this study, recently published by the Journal of the American Medical Association, showed that all of these main pollutants, with the exception of ozone, increased risk for heart attack. In fact, they found that 0.6–4.5% of heart attacks in the study population were due to exposure to air pollution.

If further research studies confirm these findings, it is possible that public health officials may change pollution guidelines in an effort to improve air quality. Individuals with high cardiovascular risk, such as those with heart disease and/or history of heart attack, may also be advised to avoid exposure to pollution by staying inside especially on warmer days of the year, when air pollution is more abundant. But until then, individuals should continue to address any cardiovascular risk factors that are within their power, such as high blood pressure and being overweight, to help reduce their risk for heart disease, heart attack and stroke.

Questions for You to Consider

Why would air pollution trigger heart attacks?

Although further research is needed to better understand the relationship between pollution and heart attacks, experts believe that short-term exposure to air pollution may trigger inflammation and promote blood clotting, increasing risk for a cardiac event.

How can I reduce my exposure to air pollutants?

Although it is impossible to completely avoid exposure to any air pollutants, you can check local air quality conditions on the news or weather and try to go outside when air quality conditions are best (often early morning or evening and in cooler temperatures). Also, avoid being outside around traffic-congested streets where pollution can be heavy.